This application is for the renewal of the Center for Analysis and Management of the Multicenter AIDS Cohort Study (CAMACS). The MACS, an ongoing cohort study in which 6948 men have been enrolled as of June 30, 2003 at sites located in Baltimore, Chicago, Los Angeles, and Pittsburgh, has made significant contributions to the natural history of HIV infection. The multicenter collaborative aspects, the enrollment of multiple, fixed cohorts, the data complexity involved in the MACS and the selective use of treatment require a data coordination center to integrate the HIV science with expertise in epidemiology, statistics and data management to address the scientific agenda as set forth in the Unified MACS Proposal - Part A. The specific aims of CAMACS are: 1) to coordinate MACS-wide research, including data acquisition, periodic reporting on the status of the MACS study population and database, and distribution of data and specimens for research; 2) to manage the data collected in the study using established procedures for transferring, editing, merging, storing and backing up the data; and to implement procedures for quality assurance in all aspects; 3) to collaborate with MACS and external investigators by providing statistical and epidemiological expertise in the design, analysis and interpretation of studies related to the core aims of the study; and 4) to provide an infrastructure and resources to promote use of MACS data and specimens in scientific studies of HIV infection and for tracking the progress of approved projects. CAMACS will continue to develop innovative methodology as put forth in section D.9 of the Unified Proposal. The CAMACS investigative team has extensive expertise and experience in research coordination, systems and data management, epidemiology and biostatistical methods for complex longitudinal data and survival analysis. Successful methods developed for protocol development include study design and power computations, standardized data acquisition, management and summarization and quality assurance will be continued and applied to the study of metabolic and cardiovascular adverse events of HAART. CAMACS will actively participate in the study governance and provide leadership in the oversight of study protocols, analyses, and presentation of study results as a member of the Executive Committee, chair of the Data Working Group, membership to each scientific Working Group, and in writing committees.